Vitamin D Insufficiency in Pre- and Early Adolescent Children

描述（由申请人提供）：我的长期目标是成为一名熟练的独立临床研究人员，解决维生素D和钙营养方面的种族和民族差异。我的职业发展计划包括临床研究理学硕士和指导临床和社会研究。我计划研究青春期前和早期非洲裔美国人和白人儿童的维生素D状况。流行病学和临床数据表明，美国成年人和青少年中维生素D缺乏的患病率很高。关于青春期前儿童维生素D不足的患病率、季节变化和代谢影响知之甚少。在第1阶段，我们将采用纵向研究设计，估计6至12岁儿童维生素D缺乏的患病率和季节性变化，并描述其对骨代谢的影响。将在夏季（6月至9月）和冬季（12月至3月）对140名健康青春期前和青春期早期儿童（6-12岁，坦纳I或II，非裔美国人[n=94]和高加索人[n=46]）进行研究。维生素D状态，钙营养激素和骨转换标志物将在夏季和冬季进行评估。其他指标包括维生素D和钙的饮食摄入量，阳光照射和体重指数。这项研究将有助于确定学龄期非洲裔美国人和高加索儿童维生素D不足的患病率、季节变化和代谢影响。在第2阶段，168名（非裔美国人：84名，白人：84名）8至14岁的青春期前和青春期儿童将在秋季和冬季（10月至3月）开始接受为期6个月的随机安慰剂对照试验（RCT），每日ID维生素D31000与安慰剂。这项研究将确定血清25（OH）D的维生素D不足的定义，并记录维生素D状态治疗的安全性和有效性。为了解决健康差异的问题，我们将使用研究设计来检验这一假设，即与白人儿童相比，父母对医学和研究的不信任是招募非裔美国儿童参加临床研究的障碍。将对参与维生素D研究的儿童的父母进行调查。将确定同意和拒绝父母群体之间信任指数的差异。研究结果应有助于制定克服这些障碍的战略。预防儿童维生素D不足将改善他们的骨骼健康（增加峰值骨量），并减少他们成年后的“骨质疏松症负担”。优化非洲裔美国儿童的维生素D状况可能有可能减少与慢性维生素D不足相关的非骨骼疾病的差异，如糖尿病和前列腺癌，这些疾病不成比例地影响非洲裔美国成年人。

DESCRIPTION (provided by applicant): My long- term goal is to become a proficient independent clinical researcher addressing racial and ethnic differences in vitamin D and calcium nutrition. My career development plan includes a Master of Science in Clinical Research and mentored clinical and social research. I plan to study the vitamin D status of pre- and early adolescent African American and Caucasian children. Epidemiologic and clinical data document a high prevalence of vitamin D insufficiency among adults and adolescents in the US. Little is known about the prevalence, seasonal variation and the metabolic impact of vitamin D insufficiency in preadolescent children. In Phase 1, using a longitudinal study design, we will estimate the prevalence and seasonal variation of vitamin D insufficiency in children 6 to 12 years old and characterize its impact on bone metabolism. A cohort of 140 healthy pre- and early adolescent children (6-12 yrs old, Tanner I or II, African American [n=94] and Caucasian [n=46]) will be studied during summer (June through September) and winter (December through March). Vitamin D status, calcitrophic hormones and markers of bone turnover will be assessed during summer and winter. Other measures include dietary intakes of vitamin D and calcium, sun exposure and body mass index. This study will help establish the prevalence, seasonal variation, metabolic impact of vitamin D insufficiency in young school-age African American and Caucasian children. In phase 2,168 (African American: 84, Caucasian: 84) 8 to 14 year old preadolescent and adolescent children will undergo a randomized-placebo controlled trial (RCT) of vitamin D31000 ID daily vs. placebo for 6 months initiated during fall and winter (October through March). This study will determine the serum 25(OH)D cutoff for the definition of vitamin D insufficiency and document the safety and efficacy of treatment on vitamin D status. To address issues of health disparities we will use the study design to test the hypothesis that parental mistrust in medicine and research is a barrier to recruitment of African American children into clinical research compared to Caucasian children. Parents of children recruited for the vitamin D study will be surveyed. Differences in the trust index between consenting and declining groups of parents will be determined. The results should help develop strategies for overcoming those barriers. Prevention of vitamin D insufficiency in children will improve their bone health (increase the peak bone mass) and reduce their "osteoporosis burden" during adulthood. Optimizing vitamin D status in African American children may have the potential to reduce the disparities from non-skeletal disorders associated with chronic vitamin D insufficiency such as diabetes and prostate cancer that disproportionately affect African American adults.